accel/ivpu: Don't flood dmesg with VPU ready message

Use ivpu_dbg() to print the VPU ready message so it doesn't pollute
the dmesg.

Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230925121137.872158-3-stanislaw.gruszka@linux.intel.com